Intelligent non-disruptive automatic dependent surveillance-broadcast (ADS-B) integration for unmanned aircraft systems (UAS)

ABSTRACT

A system for intelligent non-disruptive airspace integration of unmanned aircraft systems (UAS) is disclosed. The system includes an onboard positioning system and altimeter that determine a current position and altitude of the UAS. Under normal conditions, the UAS remains in inert mode: a transceiver listens for and decodes transmissions from nearby aircraft and ground-based traffic and control facilities. If certain conditions are met (e.g., proximate aircraft, altitude ceilings, controlled or restricted airspaces) the system may declare an alert mode. When in alert mode, the transceiver broadcasts position and identifier information of the UAS to alert neighboring aircraft to its presence. Intelligent transmission strategies regulate the power level or rate of alert-mode transmissions to reduce spectrum congestion due to high UAS density. Alert-mode transmissions continue until the underlying conditions change and inert mode is resumed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to and claims the benefit of theearliest available effective filing dates from the following listedapplications (the “Related Applications”) (e.g., claims earliestavailable priority dates for other than provisional patent applications(e.g., under 35 USC § 120 as a continuation in part) or claims benefitsunder 35 USC § 119(e) for provisional patent applications, for any andall parent, grandparent, great-grandparent, etc. applications of theRelated Applications).

RELATED APPLICATIONS

United States patent application entitled DIRECT-BROADCAST REMOTEIDENTIFICATION (RID) DEVICE FOR UNMANNED AIRCRAFT SYSTEMS (UAS), namingPaul Beard and Christian Ramsey as inventors, filed Feb. 26, 2018,application Ser. No. 15/905,340;

United States patent application entitled AUTOMATIC DEPENDENTSURVEILLANCE-BROADCAST (ADS-B) TRANSMISSION WITHIN WHITESPACE, namingPaul Beard as an inventor, filed Aug. 24, 2016, application Ser. No.15/246,095;

United States Provisional Patent Application entitled INTELLIGENT ADS-BFOR UAS-AIRSPACE INTEGRATION, naming Christian Ramsey and Paul Beard asinventors, filed Mar. 5, 2018, Application Ser. No. 62/638,654;

United States Provisional Patent Application entitled REMOTEIDENTIFICATION, naming Paul Beard as an inventor, filed Mar. 31, 2017,Application Ser. No. 62/480,031; and

United States Provisional Patent Application entitled AUTOMATICDEPENDENT SURVEILLANCE BROADCAST TRANSMISSION WITHIN WHITESPACE, namingPaul Beard as an inventor, filed Aug. 24, 2015, Application Ser. No.62/209,221.

Said U.S. patent application Ser. Nos. 15/905,340; 15/246,095;62/638,654; 62/480,031; and 62/209,221 are herein incorporated byreference in their entirety.

BACKGROUND

Automated Dependent Surveillance-Broadcast (ADS-B) has been the subjectof much debate in recent years as to whether it provides a suitablecooperative surveillance solution for preventing mid-air collisionsbetween manned aircraft and unmanned aircraft (e.g., unmanned aircraftsystems (UAS), unmanned aerial vehicles (UAV)). ADS-B is asatellite-based system using global positioning technology (e.g., GPS)to precisely determine an aircraft's position, airspeed, and otherattributes and relay this information (e.g., “ADS-B Out”) toground-based stations (which relay the data to air traffic control (ATC)displays) or directly to other aircraft (e.g., “ADS-B In”). In thelatter case, pilots whose aircraft are so equipped may receive directweather and traffic data in the cockpit. Ground-based ADS-Binfrastructure is fully operational in the United States, wherein anyaircraft flying in controlled airspace must incorporate ADS-B equipmentby Jan. 1, 2020.

However, with respect to unmanned aircraft, particularly smaller-scalevehicles and hobbycraft, the utility of ADS-B at altitudes under 500feet above ground level (AGL) may be limited if dependent uponground-based infrastructure, as the system and infrastructure wereoriginally designed to enhance and match existing radar coverage of theNational Airspace System (NAS) and ATC. In addition, ADS-B is adual-band system in that aircraft flying above 18,000 feet mean sealevel (MSL) must broadcast via ADS-B Out at 1090 MHz, while aircraftbelow this altitude may broadcast either at 1090 MHz or via 978 MHzUniversal Access Transceiver (UAT). As a result, some aircraft equippedfor air-to-air reception at one frequency may not “hear” positionreports at the other frequency. To mitigate this problem, some ADS-Bavionics may “listen” at both frequencies although they may transmit at1090 MHz only. Further, ground-based stations may rebroadcast positionreports between frequencies (Automatic DependentSurveillance-Rebroadcast, or ADS-R) if aircraft operating on differentfrequencies are in proximity to each other, adding latency to thesystem.

While ADS-B may be a promising solution for safely integrating UAS intothe NAS, there may be consequences not previously projected orconsidered. For example, a high density of UAS operating within a givenairspace at low altitudes, and broadcasting position information even atreduced intervals, may result in co-channel interference sufficient toadversely impact air-to-air ADS-B performance between manned civilianaircraft.

SUMMARY

A system for intelligent non-disruptive airspace integration of unmannedaircraft systems (UAS) is disclosed. In embodiments, the system includesan onboard positioning system that determines, via satellite-basednavigation or subsystems of like precision, a current position of theUAS. The system includes an altimeter aboard the UAS for determining acurrent altitude of the UAS. The system includes onboard data storagefor storing configuration data of the UAS, such as a unique identifier,and terrain and aircraft databases with additional information about thesurrounding environment and its attendant air traffic. The systemincludes a transceiver including one or more processors, the transceivercapable of receiving transmissions from nearby aircraft and ground-basedtraffic and control facilities. The transceiver decodes these inboundtransmissions to identify proximate aircraft (and whether said aircraftare manned or unmanned) as well as controlled or restricted airspaces inor near the flightpath of the UAS. The transceiver continually assessesa transmission state of the UAS, which may be a default or “inert” stateor, if certain conditions are met, an “alert” state. When in the “alert”state the transceiver encodes current position/altitude and identifierinformation into a message format which is broadcast to alert theproximate vehicles to the presence of the UAS. The transceiver employsintelligent transmission strategies to reduce spectrum congestion; whenin the “alert” state the UAS will transmit at preconfigured intervals orpower levels (e.g., reduced power, reduced frequency) based on airtraffic or airspace control restrictions. The “alert” state continuesuntil the conditions driving the “alert” state end, wherein the “inert”state resumes.

In embodiments, the “alert” state is declared based on the proximity ofneighboring aircraft (e.g., distance and/or altitude).

In embodiments, the “alert” state is declared when the UAS exceeds apreconfigured or imposed altitude threshold.

In embodiments, the transceiver is wirelessly linked to a remoteoperator or pilot in command (PIC) via a control device capable ofaccepting command input from the PIC (e.g., via a command/control (C2)link).

In embodiments, the “alert” state is declared based on a loss of the C2link.

In embodiments, the “inert” state is resumed based on re-establishmentof the C2 link.

In embodiments, the “alert” state is manually declared by the PIC.

In embodiments, the transceiver identifies the particular frequency atwhich the received transmission was sent, and transmits an alert-moderesponse at the identified frequency.

In embodiments, the system is embodied in an attachable apparatusconnectable to the UAS control system via physical data link.

In embodiments, the altimeter is a barometric altimeter or likealtimeter capable of determining a pressure altitude.

In embodiments, the altimeter determines the current altitude viacorrelation with other like altitude sensors, e.g., a radar altimeter,the UAS control system, or the terrain database.

In embodiments, the transceiver transmits alert mode responses at a lowpower level under 1 watt.

In embodiments, the transceiver determines the unique identifier of thetransmitting aircraft by decoding the incoming transmission anddetermines whether the transmitting aircraft is manned or unmanned.

In embodiments, if the aircraft is unmanned, the transceiver does nottransmit alert-mode responses.

In embodiments, if the aircraft is unmanned, the transceiver transmitsalert-mode responses at a particular preconfigured power level andfrequency.

This Summary is provided solely as an introduction to subject matterthat is fully described in the Detailed Description and Drawings. TheSummary should not be considered to describe essential features nor beused to determine the scope of the Claims. Moreover, it is to beunderstood that both the foregoing Summary and the following DetailedDescription are example and explanatory only and are not necessarilyrestrictive of the subject matter claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. The use of the same reference numbers in different instances inthe description and the figures may indicate similar or identical items.Various embodiments or examples (“examples”) of the present disclosureare disclosed in the following detailed description and the accompanyingdrawings. The drawings are not necessarily to scale. In general,operations of disclosed processes may be performed in an arbitraryorder, unless otherwise provided in the claims. In the drawings:

FIG. 1 is a block diagram illustrating an inert/alert system for anunmanned aircraft system (UAS), in accordance with example embodimentsof this disclosure; and

FIGS. 2A and 2B are diagrammatic illustrations of operations of theinert/alert system of FIG. 1 in accordance with example embodiments ofthis disclosure.

DETAILED DESCRIPTION

Before explaining one or more embodiments of the disclosure in detail,it is to be understood that the embodiments are not limited in theirapplication to the details of construction and the arrangement of thecomponents or steps or methodologies set forth in the followingdescription or illustrated in the drawings. In the following detaileddescription of embodiments, numerous specific details may be set forthin order to provide a more thorough understanding of the disclosure.However, it will be apparent to one of ordinary skill in the art havingthe benefit of the instant disclosure that the embodiments disclosedherein may be practiced without some of these specific details. In otherinstances, well-known features may not be described in detail to avoidunnecessarily complicating the instant disclosure.

As used herein a letter following a reference numeral is intended toreference an embodiment of the feature or element that may be similar,but not necessarily identical, to a previously described element orfeature bearing the same reference numeral (e.g., 1, 1 a, 1 b). Suchshorthand notations are used for purposes of convenience only and shouldnot be construed to limit the disclosure in any way unless expresslystated to the contrary.

Further, unless expressly stated to the contrary, “or” refers to aninclusive or and not to an exclusive or. For example, a condition A or Bis satisfied by anyone of the following: A is true (or present) and B isfalse (or not present), A is false (or not present) and B is true (orpresent), and both A and B are true (or present).

In addition, use of “a” or “an” may be employed to describe elements andcomponents of embodiments disclosed herein. This is done merely forconvenience and “a” and “an” are intended to include “one” or “at leastone,” and the singular also includes the plural unless it is obviousthat it is meant otherwise.

Finally, as used herein any reference to “one embodiment” or “someembodiments” means that a particular element, feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment disclosed herein. The appearances of thephrase “in some embodiments” in various places in the specification arenot necessarily all referring to the same embodiment, and embodimentsmay include one or more of the features expressly described orinherently present herein, or any combination of sub-combination of twoor more such features, along with any other features which may notnecessarily be expressly described or inherently present in the instantdisclosure.

An intelligent, non-disruptive “inert/alert” system for airspaceintegration of a UAS is disclosed. Broadly, embodiments of the inventiveconcepts disclosed herein may mitigate spectrum congestion concerns dueto the proliferation of small UAS (SUAS) equipped with ADS-Bfunctionality within an airspace. In particular, embodiments ofintelligent ADS-B systems may reduce co-channel interference bytransmitting or broadcasting only when there is an imperative to do so,e.g., for safety or compliance reasons. Operating either on a standalonebasis or integrated into UAS control systems, intelligent ADS-B“inert/alert” systems may reduce transmission power and range generallyto reduce interference, or broadcast only when transmission isdetermined to be necessary. When particular conditions are met, thesystem shifts from a default “inert mode” into “alert mode”,broadcasting regular position updates until the underlying conditionsare no longer present and “inert mode” is resumed.

Referring to FIG. 1, the inert/alert system 100 may include apositioning system 102, an altimeter 104, a transceiver 106, a memory108 or other like data storage, and antenna elements 110. Theinert/alert system 100 may be incorporated into the onboard controlsystem 112 of a SUAS or other unmanned aircraft, or embodied in a deviceattachable or mountable to the SUAS airframe, capable of communicationwith the SUAS control system via one or more physical data links 114.The inert/alert system 100 may be wirelessly linked, along with the SUAScontrol system 112, to a remote operator 116 (e.g., pilot-in-command(PIC)) providing command input to the SUAS control system 112, e.g., viaa portable computing device or other similar controller deviceincorporating control processors.

The positioning system 102 may be a Global Positioning System (GPS) orother satellite-based position receiver capable of determining a currentposition (e.g., latitude/longitude) of the SUAS of sufficient precisionfor ADS-B compatibility. The positioning system 102 may continuallydetermine the position of the SUAS, which may include logging thecurrent position to memory (108) or updating the remote operator 116.

Similarly, the altimeter 104 may monitor (e.g., log, update) the currentaltitude of the SUAS. The altimeter 104 may be a barometric device,Mode-C transponder, or similar sensor capable of determining andreporting a barometric altitude. In some embodiments, the altimeter 104may include, or may correlate a reported barometric altitude with, otheronboard sensors such as a radar altimeter. Similarly, the altimeter 104may include a processor capable of correlating the reported barometricaltitude, with, e.g., Mode-C transponder transmissions received fromproximate aircraft, with an autopilot system or the control system 112of the SUAS, with terrain databases stored to memory 108 andcross-referenced with the GPS-derived position.

Under normal operational conditions, the inert/alert system 100 mayremain in a default or “inert” mode. For example, while in “inert” mode,the transceiver 106 may continuously “listen to” and monitor incomingtransmissions to assess the current position and altitude of the SUASrelative to proximate and neighboring aircraft. The transceiver 106 may,via the antenna elements 110, receive ADS-B and ADS-R transmissions,transponder messages (e.g., Mode A/C/S) from other aircraft, FlightInformation System-Broadcast (FIS-B) and Traffic InformationSystem-Broadcast (TIS-B) transmissions from ground control facilities.The transceiver 106 may include processors capable of decoding inboundtransmissions to compare the current position of the SUAS to nearbyaircraft and assess, on a continuous or interval basis, whether anycondition exists providing for a declaration of “alert mode”. Similarly,the transceiver 106 may determine, based on the current position andaltitude sensed by the positioning system 102 and altimeter 104,additional attributes of the SUAS (e.g., if preconfigured to do so bythe remote operator 116). For example, the transceiver 106 may calculateor log a current airspeed or rate of climb/descent.

Referring also to FIGS. 2A and 2B, a small unmanned aircraft system 200(SUAS) incorporating the inert/alert system 100 of FIG. 1 is shown.Based on position assessments by the transceiver 106, the inert/alertsystem 100 may continually reaffirm the default “inert” mode or declarethat the SUAS is in an “alert” mode if any of a variety of predeterminedconditions, or some predetermined combination of conditions, arepresent. For example, any of the following conditions may trigger thedeclaration of “alert” mode:

The inert/alert system 100 detects nearby traffic (e.g., an unmannedaircraft 202 or manned commercial aircraft 204) within a predeterminedpositional or altitude range, e.g., with 7 nautical miles (NM) or 2,000ft of altitude. For example, if the manned commercial aircraft 204 istraveling at 150 NM on a direct collision course with the SUAS 200(itself traveling at its Part 107 (14 CFR § 107) maximum allowedairspeed of 87 NM), the manned aircraft would be left with 1.77 minutes(˜1 min 46 sec) to execute evasive or avoidance maneuvers.

The inert/alert system 100 determines that the SUAS 200 has exceeded apreconfigured altitude ceiling 206, e.g., exceeding 400 ft above groundlevel (AGL), the altitude ceiling imposed by the United States FederalAviation Administration (FAA).

The inert/alert system 100 determines that the SUAS 200 is approaching,or has breached, a controlled airspace 208, or that the SUAS 200 isapproaching, or has breached, a Temporary Flight Restriction 210 (TFR)or otherwise geofenced/prohibited airspace.

The inert/alert system 100 determines that the link to the remoteoperator 116 is lost (e.g., a command/control (C2) link), or thatpositive control by the remote operator/PIC is otherwise compromised.

In addition, the remote operator 116 may manually declare an “alert”mode.

In some embodiments, the declaration of an “alert” mode by theinert/alert system 100 may direct the transceiver 106 to encode thecurrent position and altitude (and, e.g., other pertinent information,such as airspeed) along with an identification code (e.g., tail number,ICAO identifier) uniquely identifying the SUAS. The encoded informationmay be transmitted by the transceiver 106 (e.g., in ADS-B or anysimilarly appropriate commonly recognizable or decodable message format)at preconfigured intervals while the alert conditions remain present (oruntil the inert/alert system 100 declares an “inert” mode).

In some embodiments, while broadcasting to proximate aircraft (e.g.,unmanned aircraft 202 or manned commercial aircraft 204) that the SUAS200 is nearby (and possibly that, based on its airspeed and/or heading,a collision may be imminent), the inert/alert system 100 may takeadditional measures to guard against spectrum congestion or co-channelinterference. For example, the inert/alert system 100 may transmit atlower power settings or at less frequent intervals than the standardADS-B Out interval of one second, e.g., transmitting at 1 W power at10-second intervals. Lower-power transmissions, e.g., 0.5 W or even aslow as 0.01 W, may be employed by the transceiver 106 to minimize impacton spectral capacity in situations where the limited range of suchtransmissions presents no risk to the safety of the SUAS 200 or toproximate air traffic.

In some embodiments, the declaration of “alert” mode by the inert/alertsystem 100 is combined with selective deployment of transmissions toprevent spectrum congestion. For example, by decoding an incoming ADS-Bmessage from a proximate manned aircraft 204, the transceiver 106 mayconfirm that the message was transmitted at 1090 MHz and transmit analert-mode response (e.g., the current position and identifier of theSUAS 200) at the same frequency to alleviate the need for acorresponding ADS-R transmission (e.g., if the alert-mode responses weretransmitted at 978 MHz) and the attendant system latency.

Similarly, the proximate aircraft (e.g., the unmanned aircraft 202) maypresent a Mode-C/Mode-S transponder transmission source that does notcorrelate with any ADS-B transmission source identified by theinert/alert system 100. If the transponder-indicated altitude is withinthe proximate envelope of the SUAS 200 (e.g., within 2,000 feet), theinert/alert system 100 may declare an “alert” mode and begintransmitting the current position and identifier, e.g., via ADS-B. Whilethe unmanned aircraft 202 may not be ADS-B enabled, its remote operatormay be equipped with a portable communications device having ADS-B Incapacity and would thereby be able to “see” the SUAS 200. Theinert/alert system 100 may further integrate with noncooperative radaraboard the SUAS 200, e.g., for transmission when in the vicinity of anoncooperative target.

In some embodiments, the inert/alert system 100 may monitor TFRs 210 orcontrolled airspaces 208 via preflight configuration, e.g., loading intomemory 108 any known TFRs and/or controlled airspace boundaries andrestrictions prior to takeoff. Similarly, the inert/alert system 100 maymonitor any additional TFRs 210 or corresponding information by decodingreceived FIS-B messages via the transceiver 106. While flying throughthe controlled airspace 208, if an “alert” mode is declared theinert/alert system 100 may transmit the current position and uniqueidentifier in compliance with any known restrictions imposed by thecontrolled airspace (e.g., power level, frequency, interval).

In some embodiments, the inert/alert system 100 may incorporategeospatial buffering (212) in order that alert-mode responsetransmissions are compliant with controlled-airspace restrictions priorto actual entry into the controlled airspace 206.

In some embodiments, referring in particular to FIG. 2A, the inert/alertsystem 100 may, when in “alert” mode, selectively transmit alert-moderesponses based on other information derived from transmissions receivedand decoded by the transceiver 106 (FIG. 1). For example, the ADS-Bmessage format includes a field “emitter category” which defines a typeof aircraft (e.g., the transmission source). The inert/alert system 100may reduce spectrum congestion by transmitting alert-mode responsesbased on the proximity of the manned aircraft 204 to the SUAS 200, butnot transmitting alert-mode responses if only the unmanned aircraft 202is determined to be sufficiently proximate to the SUAS (e.g., assumingadditional or other means and technologies available for mutual remoteidentification of the SUAS 200 and the unmanned aircraft 202). In someembodiments, the inert/alert system 100 may leverage emitter categoryinformation under high-density conditions such that, for example, theproximity of the unmanned aircraft 202 to the SUAS 200 may triggeralert-mode transmissions between the SUAS and the unmanned aircraft butnot induce a chain reaction with other unmanned aircraft not within theproximity envelope of the SUAS 200.

It is to be understood that embodiments of the methods disclosed hereinmay include one or more of the steps described herein. Further, suchsteps may be carried out in any desired order and two or more of thesteps may be carried out simultaneously with one another. Two or more ofthe steps disclosed herein may be combined in a single step, and in someembodiments, one or more of the steps may be carried out as two or moresub-steps. Further, other steps or sub-steps may be carried in additionto, or as substitutes to one or more of the steps disclosed herein.

Although inventive concepts have been described with reference to theembodiments illustrated in the attached drawing figures, equivalents maybe employed and substitutions made herein without departing from thescope of the claims. Components illustrated and described herein aremerely examples of a system/device and components that may be used toimplement embodiments of the inventive concepts and may be replaced withother devices and components without departing from the scope of theclaims. Furthermore, any dimensions, degrees, and/or numerical rangesprovided herein are to be understood as non-limiting examples unlessotherwise specified in the claims.

We claim:
 1. A system for intelligent non-disruptive airspaceintegration of unmanned aircraft systems (UAS), comprising: apositioning system situated aboard a UAS and configured to determine acurrent position of the UAS; at least one altimeter situated aboard theUAS and configured to determine a current altitude of the UAS; a memorysituated aboard the UAS and configured to store configuration dataassociated with the UAS, the configuration data including at least aunique identifier corresponding to the UAS; and at least one transceivercoupled to the positioning system and the altimeter, the transceiverincluding at least one processor and configured to: receive one or moretransmissions from at least one of a first aircraft and a ground-basedtraffic control facility; identify an alert state associated with atleast one of: a) a proximate position of the first aircraft; and b) acurrent position associated with at least one of a controlled airspaceand a restricted airspace; continually determine a transmission state ofthe UAS, the transmission state corresponding to one of a default stateor the alert state, and while the transmission state corresponds to thealert state, transmitting at least the current position and the uniqueidentifier at one or more of a response frequency, a response powerlevel, and a predetermined interval.
 2. The system of claim 1, whereinthe default state is associated with non-transmission of the currentposition and the unique identifier.
 3. The system of claim 1, whereinthe alert state is associated with the proximate position of the firstaircraft within a predetermined range of one or more of the currentaltitude and the current position.
 4. The system of claim 1, wherein thealert state is associated with the current altitude exceeding analtitude threshold.
 5. The system of claim 1, wherein the transceiver iswirelessly coupled to an operator remotely located from the UAS via awireless link to a control device configured to accept command inputfrom the operator.
 6. The system of claim 5, wherein the alert state isassociated with a loss of the wireless link.
 7. The system of claim 6,wherein the default state is determined based on a subsequentreestablishment of the wireless link.
 8. The system of claim 5, whereinthe alert state is manually determined by the operator via the controldevice.
 9. The system of claim 1, wherein the transceiver is configuredto: identify a transmitted frequency associated with the receivedtransmissions; and the predetermined frequency corresponds to thetransmitted frequency.
 10. The system of claim 1, wherein the system isembedded in an apparatus removably attachable to an airframe of the UASand couplable thereto by at least one data link.
 11. The system of claim1, wherein the altimeter includes a barometric altimeter.
 12. The systemof claim 1, wherein the altimeter is configured to determine the currentaltitude by correlating a sensed first altitude with a second altitudeassociated with at least one of a radar altimeter, a control system ofthe UAS, and a terrain database stored to the memory.
 13. The system ofclaim 1, wherein the response power level is not more than one watt. 14.The system of claim 1, wherein the unique identifier is a first uniqueidentifier and the transceiver is configured to: identify, by decodingthe received transmissions, a second unique identifier of the firstaircraft; and determine, based on the second unique identifier, whetherthe first aircraft is a manned aircraft or an unmanned aircraft.
 15. Thesystem of claim 14, wherein: when the first aircraft is an unmannedaircraft, the transceiver is configured to not transmit the currentposition and the first unique identifier.
 16. The system of claim 14,wherein the response power level is a first response power level and theresponse interval is a first response interval: when the first aircraftis an unmanned aircraft, the transceiver is configured to transmit thecurrent position and the first unique identifier according to at leastone of a second response power level and a second response interval.